Gardening Answers Knowledgebase

I have grey-green fairly large caterpillars eating my foxgloves. They are eating them to shreds but I have hopes that they will still flower. They are leaving what looks like rodent droppings in the leaves. They are eating only the foxgloves. My question is what are they and is it okay to keep the plants or should I pull them up?

Answer:

I strongly suspect you have variegated (or climbing) cutworms. I have these nasty bugs too and can give you a long list of plants they eat. Foxgloves are their favorite. Here are some management solutions in order of most work, least toxic to less work, but more toxic:

1) hand-pick after dark (with a flashlight) starting in January and continuing through May.
2) spray Bt (Bacillus thuringiensis) (found in Caterpillar Killer). It must be reapplied after rain. Be careful where you spray it because it will also kill butterfly caterpillars.
3) general pesticides will kill cutworms and many other critters that come along, including bees and may harm birds.

I have about 20 healthy artichokes. They did not die back in the winter. I think that there is a lot of bug activity going on in them: earwigs, slugs. Should I cut the plants to the ground and dispose of the possible bugs that have wintered over in them? I hate to do it because the foliage is so lovely.

Answer:

I have grown artichokes for the last 5 years, so I am going to answer from personal experience.
Do not cut the plants back because they will be sending up their flowers in the next few weeks (depending on the weather, it could be as late as June). Cutting it back now will just delay any flowers for at least 6-8 months, if not kill them outright. While I too have had numerous slugs, earwigs and cutworms, I find that their damage is minimal, and does not hurt the flower show. And for eating I just wash them carefully and then turn a blind eye when I find a few earwigs in the pot after cooking!
Sprinkling some Sluggo (or comparable less toxic slug bait) into the leaf joints will help too.

My small patch of strawberry plants has this year suffered
from green fruit dropping off, forming neat piles under each plant. Each
fallen fruit has a short bit of stem still attached. A few fruit are still
attached. No sign of slug or squirrel damage, no signs of fungus of
insect attack. The weather has been colder and wetter than average. Owing
to natural layering, the plants are closer together than when first
planted. This happened a couple of years ago, but we had a good crop last
year. Any idea what's going wrong?

Answer:

I wonder if this might be the work of cutworms. You can take a close look
just under the soil surface, along the stems, and inside curled or folded
leaves during the day, or take a flashlight at night, which is when they
feed, and see if that may be why your strawberries are being cut away
from the plant. If you find them, cut them with garden pruners.

"Cutworms and armyworms are the larvae of noctuid moths. These common
moths are medium-sized with fairly dull coloration. The greenish,
grayish, or tan caterpillars are hairless, nocturnal, and generally
spotted, striped, or otherwise marked. They may be 1/4" to 1" in length
and tend to curl up when disturbed. They may climb into the plant and
feed on foliage, buds, flowers, or fruit. Armyworm behavior is similar to
that of cutworms, but armyworms feed in large groups instead of
individually. They tend to be voracious feeders. The caterpillars
typically spend the day just beneath the soil surface or under debris
near the host. Weeds are a primary food source for both cutworms and
armyworms."

I looked at Pests of the Garden and Small Farm by Mary Louise Flint
(University of California, 1990), but could not find any strawberry
disease resembling what you have observed in your garden, which leads me
to believe it is a pest problem. Here is a link to U.C. Davis's
Integrated Pest Management page on strawberries.

Garden Tool: Variegated cutworms are in full force in the garden this time of year(Feb-May). Some of their favorite foods include primrose, foxglove, variegated water figwort, bearded iris, and chives. The little vandals only feed at night, so if you have suspicious holes on the leaves of your plants go out at night with a flashlight. Hand picking works, but must be done frequently. Spraying with Bt (Bacillus thuringiensis - Green Light BT Worm Killer is one name brand) works too, but plants must be re-sprayed after each rain. More information: North Dakota State University

Garden Tool: Warm winter days above 50 degrees make gardeners eager to get back out working in the garden. The warm temperatures also trigger many over-wintering insects and caterpillars to hatch and begin their development. Practitioners of Integrated Pest Management use "degree days," or days above 50° to forecast when a garden pest might start doing damage and when management should begin. Some pests require more accumulated heat then others to complete their lifecycles. The variegate cutworm, for example, may start feeding as early as February during mild Northwest winters. Dedicated fruit and vegetable growers will want to download degree day calculators and spread sheets from Washington State University's Entomology department.
Colorado State Cooperative Extension published an interesting article on the strategies pests use to survive cold winter days.